Estrogen-only study halted due to risk of stroke, dementia

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WASHINGTON — The government, ending the last major study of estrogen, says taking it alone isn’t as bad as using it with the hormone progestin. But officials advise that estrogen still is too risky for long-term use.

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Women who took estrogen alone after menopause had a significantly increased risk of stroke, and possibly a higher risk of dementia too, the National Institutes of Health announced Tuesday.

That doesn’t mean that women who just started using estrogen to relieve menopausal symptoms like hot flashes should panic, cautioned Dr. Barbara Alving, director of the NIH’s Women’s Health Initiative.

“This isn’t an emergency,” she said.

But there are women who have used estrogen for many years, even decades, and “this provides them with an opportunity to say, ’Do I really need to be on this still?”’ Alving added.

For now the government’s advice: If you use hormones for menopausal symptoms, use the lowest effective dose for the shortest possible duration, she stressed.

Doctors long thought that using estrogen, alone or together with progestin, would keep women healthier after menopause, in such ways as reducing heart attacks and keeping the brain sharp.

Millions of women have quit using the estrogen-progestin combination since 2002, when a major federal study concluded that those pills raised the risk of breast cancer, strokes and heart attacks.

Scientists weren’t sure whether estrogen alone was as risky. Only women who have undergone a hysterectomy can even consider taking estrogen alone; in other women, progestin use with estrogen is crucial to protect against uterine cancer.

Now, the NIH is shutting down its study of estrogen-only use, too, telling the 11,000 women enrolled to quit their pills — essentially ending hope that estrogen alone would have some overarching usefulness that the hormone combination did not.

The women, who were healthy 50- to 79-year-olds, took either estrogen or a dummy pill for nearly seven years. The study’s primary purpose was to see if estrogen could prevent heart disease after menopause.

Among the findings released Tuesday:

Estrogen alone increased the risk of a stroke as much as estrogen-progestin does. For every 10,000 women, those taking hormones suffer eight more strokes per year than nonhormone users.

Estrogen alone had no effect, good or bad, on heart disease. In contrast, the estrogen-progestin combination increases heart attack risk by 29 percent.

Estrogen alone didn’t increase the risk of breast cancer, a surprise to the NIH. Again in contrast, the estrogen-progestin combination had increased that risk, by 26 percent.

Alzheimer's risk
Neither type of hormone therapy seems good for women’s brains. Preliminary data from a related study of women 65 and older suggest those taking estrogen alone were more likely to suffer some degree of dementia than those taking a placebo, the NIH said.

Likewise, scientists announced last May that the estrogen-progestin combination doubled the risk of Alzheimer’s and other forms of dementia.

Both estrogen alone and with progestin have some benefits. Both types decrease the risk of a hip fracture from bone-thinning osteoporosis, although the NIH said only women who cannot take one of the nation’s many other osteoporosis treatments should consider estrogen for that use.

And Wyeth Pharmaceuticals, maker of the Premarin estrogen brand used in the study, stressed that estrogen remains the most effective treatment for such menopausal symptoms as hot flashes, which for some women can be a serious problem.

Women now taking hormone therapy, or considering it, for those two reasons must discuss their individual risk factors with their doctors, cautioned the American Society for Reproductive Medicine.

NIH’s Alving reiterated that, noting that women in the study were generally very healthy yet still had the increased stroke risk — a risk that would be even greater for a woman who also smokes and has high blood pressure.

“The average woman needs to look at what her own individual risks are,” she stressed.

The NIH decided to stop the estrogen-only study last month, a year before its planned completion, saying enough data had been collected to assess overall risks and benefits. The agency plans to report details of the data within two months, but released preliminary findings Tuesday to coincide with letters telling study participants to quit their pills.